Dual wheel brake assembly



ch 22, E949. c; P. TOLMAN 9 DUAL WHEEL BRAKE-ASSEMBLY Filed May 25, 1946 Patented Mar. 22, 1949 UNITED STATES PATENT OFFICE t Differential Wheel Corporation, Detroit, Mich, a corporation (if-Delaware ApplioationMayfiE, 1946, Serial No. 672,325

2'Claiins.

The present invention pertains to dual. wheel assemblies for vehicles but more particularly-and specifically to a braking system for an assembly in which the wheels are normally independently rotatable.

The type of dual wheel assemblies to which the present invention is particularly-adapted are dis-- closed in the Charles 'S; Ash United' states Letters Patents 2,192,023 dated February 27,1940,- and 2,275,025 dated February 3, 1 942, fromwhich a more comprehensive and detailed understanding and disclosure of the precise construction and operation of the braking system can be ascer tained.

In the arrangements of the devices of the-Ash patents and devices of a similar nature the constructions are such that lubrication-must beipro= vided for operating and contacting members and surfaces of the braking mechanism with the reult that this lubricant reaches-the braking-and v the cooperating clutching members or. surfaces. Elimination of this lubricant has -been Ifound to be desirable to overcome any possibility of its causing slippage of the braking and clutching elements and the present invention has as one of its objects the provision of a. construction which eliminates any possibility of lubricant reaching either the brake or clutch elements of the braking system.

A further object of the invention is thatoi providing a construction having a bearing arrrangement which will materially reduce the 1 1 10? tion contacts between the operatingparts of the wheel braking mechanism.

Another and further object of the invention is to provide a vehicle wheel braking mechanism which is sturdy, positive of operation and con-- structed to reduce servicing maintenance to a minimum.

Other objects, novel features of. construetion and improved results of the invention-- willappear from the following description when read in the light of the accompanying drawings and will be understood by those skilled in the art and can be ascertained by the practice and utilization of the invention.

One embodiment of the invention, which together with the description will serve to explain the principles of the invention form a part of the present application.

Of the drawings:

Fig. 1 is a side view of the dual wheel assembly, a portion of the view being broken away and shown in vertical section.

Fig. 2 is a fragmentary side View of theirmer' wheel web illustrating the roller bearings carried therein,

Describing the invention in detail, A is a vehicle shaft provided with a pair of spaced radial selfaligning bearings B and C upon which is rotaplied uniformly to both wheels.

embodiment of the invention the braking action 2 tively supported the elongated hub l of an inner wheelD. The inner. wheel has a web 2 which carries a rim 3, illustrated in dotted lines, for any usual or conventional tire.

.An outer wheel Eis arranged in side by side relationship to the inner wheel and. its hub 4 telescopically receives the hub of the inner wheel and is rota'tively supported thereon in part by a self-lubricating bearing 5 mounted exteriorly on the inner wheel hub. The outer end of the outer wheel hub is suitably rotatively supported in a manner, not shown, because it forms no specific part of thepresentinvention. The outer end of the hub of the outer wheel is closed with the result-that the hub of the inner wheel forms a chamber 6 surrounding the vehicle axle. This chamber serves as a receptacle for lubricant for the bearings supporting the inner wheel hub and the outer end of the outer wheel hub. Such lubricant as may reach and pass the bearing 5 is prevented from escape by a suitable oil seal 1. The outer wheel embodies a web 8 to which is attached a. rim 9, illustrated in dotted lines, which is adapted to carry a suitable conventional tire.

The invention contemplates and embodies means whereby upon the application of braking pressure, through a single braking mechanism,

to one of the independently rotating wheels the mechanism 'actsautomatically to clutch the pair o'f wheels together so that braking action is ap- In the present is applied to the inner wheel and the outer wheel isautomatically clutched to the inner wheel.

Describing in detail the arrangement for ac complish-ing the foregoing, the inner wheel is provided with a brake drum F having an inner depending wall H] which is in the form of an apertured ring. The peripheral edge of the brake wall aperture rests upon a circumferential shoulder I l formed in a support G for the brake drum. This support G is of ring-like form and substantially L-shape in cross sectional configuration. Aaflat bottom or flange forms a hub I 2 for the ring and this hub is rotatively supported upon a ring-like bearing H mounted exteriorly upon the inner end [3 of the'inner wheel hub I. This bearing is of the self-lubricating type and has a surrounding upstandin flange M which acts as: a thrust bearing through engagement with the vertical wall 15 of the brake band support G and holds this wall of the support out of contacting engagement with the inner wheel web 2.

The outer wheel web 8 carries an inwardly extending open ended drum 16 within which is positioned a clutching element in the form of a split ring I! the ends of which are in spaced relationship, for a reason hereinafter to be ex plained. This clutching element carries on its outer face a brake lining or similar material l8 adapted to be moved into clutching engagement with the inner face of the outer wheel drum [6. A forked end bracket [9 carried by the inner wheel web engages a lug carried by the clutching element and its purpose is to properly position the clutching element longitudinally of the drum l6 and prevent any appreciable longitudinal movement of the clutching element. A stop lug 2| secured to the inner wheel web 2 projects in between the spaced ends of split ring I! and engages said ends when said ring is in retracted or non-clutching position. The lug 2! serves as a stop for either end of the split ring I! when the latter is expanded into clutching position by engagement of the finger 32 with the opposite end of the ring to displace said end and expand the ring, as hereinafter more fully described. The construction and operation is entirely similar to that shown in Patent No. 2,192,023. I

Describing further themechanism which causes a clutching action upon the application of braking pressure, the inner wheel web 2 is provided with a plurality of spaced apart arcuate slots and the brake drum supporting ring G is formed with integral, spaced apart, outwardly extending spacing bosses 22 which are longitudinally apertured and carry bolts 23 which pass through suitable openings in the vertical wall ID of the brake drum and carry on their inner ends nuts 24. The bosses and their bolts 23 extend through the arcuate slots of the inner wheel web and 'the headed ends 25 of the bolt clamp a clutch operating plate 25 against the outer face of the inner wheel web 2. To provide for taking up the thrust of the brake drum supporting ring G the outer face of the inner wheel web 2 is provided with spaced apart arcuate shaped pockets each of which carries a ball-roller 3| which are in roller engagement with the bottoms of the pockets and the inner face of the clutch operating ring 26. The pockets 30, as illustrated by the arrows a and b in Figure 2, are curved on a shorter radius than the center axis of the wheel with the result that the balls are automatically centered in their pockets by centrifugal force between brake operations. These ball rollers operate without grease or other lubricant. This plate is nested within an annular shoulder 2'! formed in'the wheel web and is surrounded by an oil and dirt seal 28 which is abutted by the outer end of the outer wheel drum 16 with the result that the oil seal rings 1 and 21 seal the chamber 29 within the drum against the entry of oil or dirt thus protecting the clutch IT.

From the structure thus far described it will be seen that the brake drum F and its supporting ring G are secured together by the bolts 23 and by reason of the arcuate slots through which the :bolts and their encircling spacing bosses pass the brake drum is mounted for limited arcuate movement upon its bearing H in respect to the inner wheel web 2. A finger 32, is carried by and extends outwardly from the outer face of the clutch operating plate 26 and reaches and occupies the gap between the ends of the clutch band I1.

Whenever the brake is applied to cause the brake shoes to engage the inner wheel brake drum F, the drum is retarded and relative rotary motion of the drum and clutch operating plate 26 carried thereby with respect to web D results, the finger 32 carried by plate 26 having the same 4 relative rotary motion. As one end of the clutch band I! is held against movement by stop lug 2| as hereinbefore set forth, this rotative movement of the finger 32 causes one end of the clutch .band to be moved circumferentially which expands the band and causes it to engage the clutch drum l6 of the outer wheel with the result that braking pressure is thus applied concurrently to both wheels.

In the present construction the brake support ing ring G is held out of engagement with the wheel web and the self-lubricating bearing l2 rotatively supports the brake drum supporting ring and the thrust is taken up bythe bearing collar I4. The engagement and resulting thrust between the inner Wheel web and the clutch operating ring is through the ball rollers which reduce friction to the minimum and avoid the necessity of lubrication. In a construction wherein thrust on the brake band supporting ring and on the clutch operating ring is through actual contact with the inner wheel web, friction is exceedingly high and lubrication is provided with the consequent danger of the lubricant reaching the clutch band and thereby materially reducing its efficiency because of slippage.

The present inventive concept is not limited to the precise mechanisms illustrated and described as departures may be made therefrom within the scope of the accompanying claims vn'thout departing from the principles of the invention or sacrificing its advantages.

I claim:

1. In a dual web structure, an inner web and an outer web normally freely rotatable in respect to one another, a brake drum at the inner side of the inner web and a clutch drum carried by the inner side of the outer web and having therein a drum clutching element, said brake drum being mounted for limited rotative movement in respect to the inner web, a clutch operating plate carried by the brake drum and disposed beyond and adjacent the outer side of the inner web and having operative connection with the clutching element, a cylindrical ring bearing supporting the brake drum for said limited rotative movement, said bearing having a relatively short, outwardly radially extending flange engaging a radially inner portion of said inner web for absorbing longitudinal axial thrust upon the drum and holding the drum out of contact with the inner web side wall, the outer face of the inner web side wall being provided circumferentially with a plurality of spaced apart elongated arcuate pockets, each of said pockets being provided with a ball roller engaging and holding the clutch actuating plate out of engagement with the side wall of the inner wheel.

2. A construction as defined in claim 1 wherein, each of said pockets is curved at a radius shorter than that from the center of the pockets to the axial center of the inner wheel. CHARLES P. TOLMAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Ash Mar. 3, 1942 Number 

